Attachment plug



ATTORNEY Jan. 31, 1939.

A. E. GRANT ATTACHMENT PLUG Original Filed Oct. 2, 1936 Patented Jan. 31, 1939 UNITED STATES ATTACHMENT PLUG Albert E. Grant, New York, N. Y., assignor, by

mesne assignments, to Merwin 1F. Ashley, Boston, Mass.

Application October 2, 1936, Serial No. llll3,"l55 Renewed October 26, 193% i Claims.

My invention relates to attachment plugs of the type commonly known as end plugs" or connector caps which are carried on the ends of extension cords used for conducting current from a standard supply outlet to various types of electrically operated equipment. More particularly, the present invention is an improvement in plugs constructed in accordance with the principles taught in United States Patent No. 2,043,851 issued to Samuel W. Vanderbeek and myself, jointly, on June 9, 1936.

The prior patent teaches a construction in which rigid contact blades are resiliently mounted in a housing from which they divergently extend, the outer end portions of the blades being spaced to engage socket openings in a standard convenience outlet or receptacle, so that when the blades are coupled in such outlet or receptacle they will be drawn into substantial alignment and exert a constant resilient pressure against contacts carried in the receptacle, thereby obtaining firm mechanical connection and good electrical contact.

A principal object of my present invention is to provide an improved end plug of this character requiring fewer parts and designed for low cost production. Another object is to provide an improved structure of this type in which the resilient means is formed integral with the cap or housing member. A further object is to provide a novel and inexpensive end plug having a onepiece housing in which the end portions of the extension cord wires are completely housed and securely and permanently connected to the contact blades. Other and further objects will appear from the following specification.

Referring to the drawing which forms a part of this specification:

ill

Figure 1 is a front elevational view of an end plug embodying my invention, and

Figure 2 is a side elevationthereof.

Figure 3 is a vertical sectional view taken on line 3-3 of Figure 2 and illustrates the spacing of the outer ends of the blades in relation to the socket openings of a standard receptacle or convenience outlet, the outlet or receptacle being indicated in broken lines.

Figure 4 is a front elevational view showing the disposition of the contact blades when coupled in a standard convenience outlet or receptacle.

Figure 5 is a perspective view of one of the contact blades.

In carrying out my improvement, I provide a housing or cap member It of resilient insulating material, such as a tough resilient rubber composition. The housing is molded or otherwise formed to provide wire passages it, it and ll and blade pockets or recesses lt-lt. The housing is preferably of the elongated shape illustrated to afiord convenient exterior gripping surfaces, and the upper portion ll thereof is reduced in diameter to form a long and relatively slender neck which afiords flexible and resilient protection for a substantial length of the extension cord 2b and obviates any necessity for a separate guard to protect the cord insulation.

As shown, the passage it is formed to receive the end portion of the extension cord and extends into communication with the branch passages it and ll. The branch passages communicate with the respective blade pockets and closely accommodate end portions of the separate cord wires ill-2i which extend into the pockets and are connected to the contact blades 25. The blade pockets it are straight, deep slots which converge inwardly from the face of the housing on opposite sides of the passage it, the face of the housing being otherwise closed and continuous.

It will be noted that the branch passages of this construction divide the separate wires of the cord and maintain them spread in insulated relation to each other, so that if the usual wire insulation becomes drawn back by reason of strain on the cord, or peels, or is effected by any other cause, the wires will nevertheless be held apart in insulated relation by the passage walls.

The rigid contact blades 25 carried in the respective blade pockets extend at divergent angles from the face of the housing, the extreme outer end portions 26 of the blades being bent or flanged whereby they are disposed at reverse angles to engage against the outer walls of the socket openings 3i--tl of a standard receptacle 3%. Near the outer end of each blade and adjacent the bend therein the blade is perforate to engage with the usual protuberance formed on the receptacle contact mbmbers 31-32.

The blades may be of the usual thickness of blades in devices of this kind but are preferably stamped from thinner conducting metal of high quality and embossed, as shown, intermediate their margins over the greater portion of their contact areas to render them rigid, all as taught in my pending application Serial No. 87,879 filed June 29, 1936.

The inner end of each blade is bifurcated or notched at 21, the notch defining a pair of legs 2823, the extreme end portions of which are angularly bent to form dull prongs 28'--t8' adapted to engage the resilient inner walls of the blade pockets without tearing them and thereby prevent withdrawal of the blades from the pockets. As best illustrated in Figure 5, the inner edges of the legs 28-2B of each blade are curved convexly and converge gradually and sharply so that they will tightly grip the wire wedged and compressed between them in the notch 21. In the pocketed portions of each blade below the notch, a wire receiving aperture is formed at 29 and uninsulated end portions of the wires are threaded thru the apertures and extend thru the notched portions of the blades, substantially as illustrated in Figure 3.

To assemble the plug on the end of an extension cord, the insulation is removed from the end of the cord to expose portions of the wires. The /cord is then inserted thru the wire passage 15 and the wires are passed out thru the respective branch passages and the pockets l8. The uninsulated ends of the wires are then threaded thru the apertures 29 and drawn tightly into the notches 27. For further security the wires may be soldered to the blades, if desired. The pronged ends of the blades, together with the attached wire ends, are then forced into the blade pockets, the elastic pocket walls expanding to accommodate the prongs and the wires and tightly gripping the blades and wire ends to effect a secure and permanent assembly.

If desired, the prongs of each blade may be bent to extend in opposite directions, or both prongs may be bent outwardly rather than inwardly. Also, the uninsulated end portions of the wires may extend first thru the blade notches and thence thru the apertures 29, all such modifications being within my present contemplation.

When coupled in a standard convenience outlet or receptacle, the inwardly toed end portions of the blades are presented in the socket openings and engage against the margins of the outer walls thereof. Then, as the blades are pushed into the sockets, their contacting portions are wedged toward each other as they are caused to slide against the outer socket walls or the adjacent contacts 32, the blades pivoting and their pocketed portions being forced outwardly against the yielding resistance of the pocket walls until they are drawn into substantial parallelism, as shown in Figure 4.

So long as the plug remains in coupled relation, the walls of the blade pockets will be held in a distorted condition against their inherent resilience and will press inwardly against the blades, urging the contacting blade portions outwardly against the contact elements of the outlet or receptacle, thereby obtaining a tight mechanical coupling and good electrical connection. Upon being uncoupled, the blades of the plug are immediately forced to resume their normal angular disposition relative to the housing and the plug may be recoupled and uncoupled a large and indeterminate number of times.

Having thus described m invention, I claim:

1. An attachment plug comprising a housing of elastic and resilient insulating material having blade pockets formed therein extending convergently inward from its face, the face of said housing being otherwise closed and continuous, fiat, rigid contact blades carried in said pockets and projecting outwardly therefrom at divergent angles, the outer end portions of said blades being bent at reverse angles and normally spaced apart a distance such that they are positioned to engage margins of respective socket openings in a standard outlet to cause the blades to be drawn into substantial alignment against the yielding resistance of said housing in the act of coupling the plug in the outlet, said housing having a passage formed therein extending inwardly from the top thereof, wires extending into said passage, branch passages formed in the housing communicating between the lower end of said passage and each of said blade pockets, one of said wires extending thru each of said branch passages and connected to one of said blades within the housing.

2. An attachment plug comprising a one-piece housing of elastic and resilient insulating material, fiat, rigid contact blades carried by the housing and projecting outwardly therefrom, the outwardly projecting portions of the blades being disposed at angles to each other and their outer end portions being bent at reverse angles and normally spaced apart a distance such that they are positioned to engage margins of respective socket openings in a standard outlet to cause the blades to be drawn into substantial alignment against the yielding resistance of said housing in the act of coupling the blades in the outlet, said housing having wire passages therein communicating with the inner portions of said blades, and wires extending into the housing thru said passages, one of said wires being connected to each of said blades within the housing.

3. An attachment plug comprising a housing of elastic resilient insulating material, a pair of fiat, rigid contact blades carried by the housing and extending outwardly therefrom at divergent angles to each other, the outer end portions of the blades being bent at reverse angles and spaced apart a distance such that they are positioned to engage the outer margins of respective socket openings in a standard outlet, whereby when coupled in the outlet the blades will be drawn into substantial alignment against the yielding resistance of said housing, and means for connecting the wires of an extension cord to the portions of the blades carried within the housing.

4. An attachment plug comprising a resilient and distortable rubber housing having blade pockets formed therein and wire passages therein communicating with the pockets, said pockets extending inward at convergent angles to each other, wires extending thru said passages, and contact blades carried in said pockets and projecting therefrom at divergent angles to each other. said blades having their outer ends spaced apart a distance corresponding to the spacing between socket openings in a standard current supply outlet, said blades each comprising a strip of stifi metal having its inner end bifurcate and transversely bent to form prongs to. engaging a wall of the blade pocket, one of saio Wires extending into each of said pockets and wedged and compressed between the bifurcated portions of the blade.

- ALBERT E. GRANT. 

